Welcome to PF!!

Does the arm rise up when you have the pump fully primed?

Clean DE will tend to fall off the fingers and collect at the bottom of the filter when the pump shuts off - it's just the nature of the beast.

Here's a little info, but incomplete for your purposes use and care/ de filter It's woefully lacking on specifics for troubleshooting a problem, but works as a primer.

If your handle doesn't raise, possibly one of the "E" clips has broken - I can tell you a bunch more, once I know more about what's going on.

Are you seeing DE coming back into the pool when the system first starts?

I know these units well and will help you figure out what's wrong and how to fix it